Screening and evaluation of chilli (<i>Capsicum annuum</i> L.) genotypes for waterlogging tolerance at seedling stage

Waterlogging is an illustrious abiotic stress and the constrictions it enforces on plant roots have negative effectson growth and development. This study was undertaken to investigate waterlogging stress tolerant potential in chilli(Capsicum annum L.) genotypes through evaluating morphological, physiological, biochemical and anatomicalparameters. Thirty-five days old seedlings of 10 chilli genotypes were exposed to waterlogging stress maintainingwater height 3–5 cm over the soil surface artificially for three days. This duration (36–38 DAE) was termed aswaterlogging period, and subsequent withdrawal of waterlogging condition (39–45 DAE) was regarded as a recoveryphase. Based on their survival performance, two tolerant genotypes viz., SRC-517 and BARI morich-2 and twosusceptible genotypes viz., AHM-206 and RI-1(6) were selected for studying stress tolerance mechanism. Underwaterlogging, however, both genotypes (tolerant and susceptible) exhibited reduced root shoot length, dry weightratio, petiole weight and leaf area, and noticeable reduction regarding these parameters was observed in susceptiblegenotypes. Moreover, tolerant genotypes displayed a higher recovery than susceptible genotypes after removal ofwaterlogging stress. Lower reduction of leaf area and photosynthetic pigments as well as higher reduction of relativewater content (RWC) were noticed in susceptible genotypes. Higher accumulation of proline and total antioxidantcapacity (TAC) during waterlogging condition in tolerant genotypes suggested lower oxidative damage. Although bothgenotypes lost total soluble sugar (TSS) relative to control at waterlogging stress, better performance was recorded intolerant genotypes. During the period after the removal of extra water, a similar genotypic response in terms of TSSgain was seen. Undoubtedly, under flooding conditions, the development of aerenchyma cells in tolerant genotypes isa means of tolerance mechanism for long-term survival. Thus, the morpho-physiological and biochemical changeshelp to understand the tolerance mechanism in chilli under waterlogging stress.     

Identification of <i>PtGai</i> (a DELLA protein) in trifoliate orange and expression patterns in response to drought stress

Gibberellins (GAs) are an important hormone in regulating plant growth and development, and DELLA protein is an essential negative regulator of GA signal transduction. The aim of the study was to clone a GA-inhibiting protein DELLA from trifoliate orange (Poncirus trifoliata L. Raf.) and to analyze the bioinformations and expression patterns of the protein gene in tissues and in response to drought stress. A DELLA protein was isolated from trifoliate orange and named as PtGai (Genebank number: MZ170959). The PtGai protein had 1731 bp open reading frames, along with 576 amino acid codes, and also grouped with sweet orange (XM_006430552.4). The PtGai protein sequence was 65% homology with the sequences of DELLA proteins in other plant families. PtGai protein existed in the nucleus based on the prediction of subcellular localization. PtGai protein could be expressed in roots, stems, and leaves, along with the highest expression in stems. PtGai was upregulated by drought stress in leaves and roots, along with the decrease of root total GA concentration and the inhibition of shoot and root biomass production. It indicated the characteristics of PtGai protein and the roles of PtGai in GA synthesis and plant growth.